1. Field of the Invention
The present invention relates to a method for grinding an arcuate groove (a groove having an arcuate shape in section) defined in a work.
2. Description of the Related Art
One example of a method for forming an arcuate groove (a groove having an arcuate shape in section) in a surface of a work is a ball end milling by a machining center. This method is intended to grind an arcuate groove by moving a ball end mill in any locus along the surface of the work.
A method for cutting a spherical surface of a work by a formed cutting tool having a spring necked mechanism is described in Japanese Patent Application Laid-open No.11-90713.
An NC processing apparatus is also described in Japanese Patent Application Laid-open No.11-309602, and is comprised of a Z-axis table adapted to move a main shaft table having a main shaft for rotatably supporting a work in a Z-axis direction parallel to the main shaft. It further comprises an X-axis table adapted to move a turner supporting a cutting tool in an X-axis direction perpendicular to a Z-axis. With this NC processing machine, it is possible to form an axially asymmetric spherical surface in a work in a cutting manner by moving the cutting tool in the Z-axis direction, while moving the X-axis table in the X-axis direction in a state in which the Z-axis table has been fixed.
In processing the arcuate groove by the ball end mill, the feed pitch of the ball end mill is interpolated by a straight line. For this reason, the arcuate groove is not formed into a smooth arcuate shape. A processed line (a difference in level) corresponding to the feed pitch is produced in a depthwise direction of the feed pitch, resulting in a reduced processing quality of the arcuate groove. If the feed pitch is decreased in order to increase the processing quality, then the problem of a prolonged processing time exists.
In the method described in Japanese Patent Application Laid-open No.11-90713, the processing accuracy of the spherical surface by the formed cutting tool is improved. However, when the cutting tool is worn due to the cutting, the processing quality is thereby reduced. It is difficult to cut a material having a high hardness by the cutting tool, and there is also another problem of a hindrance to the cutting of such material.
In the method described in Japanese Patent Application Laid-open No.11-309602, the cutting is conducted by the cutting tool. Therefore, the same problems with respect to the wearing of the cutting tool are present.
In either case, when the arcuate groove has been cut in the work, it is necessary to conduct the grinding of the arcuate groove by a grindstone in order to reduce relative roughness in the cut surface of the arcuate groove.
The present invention has been accomplished with the above circumstance in view. Therefore, it is an object of the present invention to provide a processing apparatus capable of grinding an arcuate groove of any of various shapes defined in a work with a good accuracy.
To achieve the above objective, the present invention provides, for example, a method for processing an arcuate groove defined in a surface of a work so that an arc of a circle having a given radius is continuously smooth, the method using a forming grindstone to be rotated about a rotary shaft parallel to an X-axis and having the same radius as the arc of the circle, a tool table movable in the X-axis direction and in a Z-axis direction perpendicular to the X-axis with the forming grindstone supported thereon, and an indexer mounted to support the work such that the indexer is opposed to the forming grindstone in the Z-axis direction, and the indexer is moved in an Y-axis direction perpendicular to the X-axis and the Z-axis, and rotates the work W about a C-axis. The method comprises the steps of rotating the work about the C-axis, synchronizing the movement of the grindstone in the Z-axis direction, with at least one of the movement of the work in the Y-axis direction, and with the movement of the forming grindstone in the X-axis direction, and moving the forming grindstone to trace the arcuate groove.
With the above feature, the rotation of the work about the C-axis, whereby the movement of the grindstone in the Z-axis direction, and at least one of the movement of the work in the Y-axis direction, and the movement of the forming grindstone in the X-axis direction, are synchronized with one another. Accordingly, the forming grindstone is moved to trace the arcuate groove, thereby conducting the grinding of the arcuate groove. Therefore, the arcuate groove can be ground with a high accuracy. Also, it is possible to accommodate any arcuate groove of various shapes, which may lead to enhanced general-purpose properties.
The present invention also provides a work processing method including the step of moving the work in the Y-axis direction when an option between moving the work in the Y-axis direction and moving the forming grindstone in the X-axis is available.
With the above feature, it is possible to accommodate the grinding of any arcuate groove of various shapes, while maintaining the section of the arcuate groove perpendicular to a tangent direction at a shape of an exact arc of a circle, by moving the work in the Y-axis direction.
The present invention further provides a work processing method including the step of moving the forming grindstone in the X-axis direction when an option between moving the work in the Y-axis direction and moving the forming grindstone in X-axis direction is available.
With the above feature, it is possible to change the rotating surface of the forming grindstone as desired with respect to the section of the arcuate groove perpendicular to the tangent direction by moving the work in the X-axis direction, thereby accommodating the grinding of an arcuate groove elliptic in section.
In addition, the present invention provides a work processing method including the step of moving both the work in the Y-axis direction and moving the forming grindstone in the X-axis direction.
With the above feature, both of the movement of the work in the Y-axis direction and the movement of the forming grindstone in the X-axis direction are conducted. Therefore, it is possible to accommodate various shapes of the grinding of an arcuate groove, while maintaining the section of the arcuate groove perpendicular to the tangent direction. Moreover, it is possible to change the rotating surface of the forming grindstone as desired with respect to the section of the arcuate groove perpendicular to the tangent direction, thereby accommodating the grinding of an arcuate groove elliptic in section.
Furthermore, the present invention provides a work processing method including the steps of, for example, mounting a tool other than the forming grindstone on the tool table; and processing the work supported on the indexer by the tool.
With the above feature, the work supported on the indexer is processed by the tool other than the forming grindstone mounted on the tool table. Therefore, it is possible to conduct the grinding of the arcuate surface by the forming grindstone and the processing of the arcuate surface by the other tool without mounting and the removal of the work on and from the indexer. As such, this leads to an enhanced operability. Moreover, the grinding of the arcuate surface by the forming grindstone and the processing of the arcuate surface by the other tool can be carried out at the same processing standard, leading to an enhanced processing accuracy.
The present invention also provides a work processing method in which the tool is any one of a grindstone-type tool, a milling-type tool and a lathe-type tool.
With the above feature, it is possible to use each one of the grindstone-type tool, the milling-type tool and the lathe-type tool of the present invention, which leads to a substantially enhanced convenience.